Thermal decomposition of Mg(BH4)2 under He flow and H2 pressure

Nobuko Hanada, Krzysztof Chłopek, Christoph Frommen, Wiebke Lohstroh, Maximilian Fichtner

Research output: Contribution to journalArticle

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Abstract

The thermal decomposition steps of Mg(BH4)2 were investigated under He flow and various hydrogen pressures up to 50 bar. In a He flow, the main decomposition of Mg(BH4)2 occurs between 250 and 410 °C until 12.2 mass% is lost, with three main peaks of hydrogen desorption. In the first decomposition step the crystalline phase of Mg(BH 4)2 disappears while a small amount of Mg is detected in the XRD profile. However, the major part of the sample is in an amorphous state. After the second step, crystalline MgH2 is observed together with the Mg phase. The third step of hydrogen desorption corresponds to the decomposition of MgH2 and Mg remains the only crystalline phase observed by XRD measurement after heating to 410 °C. Further hydrogen evolution of 1.4 mass% is observed from 410 °C to 580 °C. Only after this hydrogen desorption, MgB2 appears in the XRD spectra of the sample. These results indicate that amorphous, hydrogen containing boron compounds take part as intermediates in the reaction. Under hydrogen pressure, the decomposition events of Mg(BH4)2 shift to higher temperatures in the DSC (differential scanning calorimetry) profiles: while there is only a small shift for steps 1 and 2 there is a clear separation of the succeeding reactions under a background pressure of hydrogen. These data show that the decomposition proceeds via several well defined steps. The final stable decomposition compound of Mg(BH4)2 is MgB2 under both inert and hydrogen gas atmosphere.

Original languageEnglish
Pages (from-to)2611-2614
Number of pages4
JournalJournal of Materials Chemistry
Volume18
Issue number22
DOIs
Publication statusPublished - 2008
Externally publishedYes

Fingerprint

thermal decomposition
Hydrogen
Pyrolysis
hydrogen
Decomposition
decomposition
Desorption
desorption
Crystalline materials
Boron Compounds
Boron compounds
boron compounds
shift
profiles
rare gases
Differential scanning calorimetry
heat measurement
Gases
Heating
atmospheres

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Materials Chemistry
  • Materials Science(all)

Cite this

Thermal decomposition of Mg(BH4)2 under He flow and H2 pressure. / Hanada, Nobuko; Chłopek, Krzysztof; Frommen, Christoph; Lohstroh, Wiebke; Fichtner, Maximilian.

In: Journal of Materials Chemistry, Vol. 18, No. 22, 2008, p. 2611-2614.

Research output: Contribution to journalArticle

Hanada, N, Chłopek, K, Frommen, C, Lohstroh, W & Fichtner, M 2008, 'Thermal decomposition of Mg(BH4)2 under He flow and H2 pressure', Journal of Materials Chemistry, vol. 18, no. 22, pp. 2611-2614. https://doi.org/10.1039/b801049h
Hanada, Nobuko ; Chłopek, Krzysztof ; Frommen, Christoph ; Lohstroh, Wiebke ; Fichtner, Maximilian. / Thermal decomposition of Mg(BH4)2 under He flow and H2 pressure. In: Journal of Materials Chemistry. 2008 ; Vol. 18, No. 22. pp. 2611-2614.
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